from S+S

THERMASREG® FS-20 - Electronic frost protection monitor

The 2-phase device provides a controlled operation of air conditioning units, heat exchangers, heating registers and similar equipment and reliably protects against frost damages and freezing. The sensor detects temperature drops below the limit value at the coldest measuring point of the capillary tube. In case of capillary breakage, power failures, or electrical damages to the sensor, the relay of the guard will automatically switch to frost.